The solid powdery cosmetic composition is a cosmetic material that is generally mold filled into a dish-shaped vessel, which is fitted into a compact container. Since it has good portability, such is widely used as makeup cosmetics such as a foundation, an eye shadow, etc. As to such a solid powdery cosmetic composition, a cosmetic base material in which an oily agent is added and dispersed into a powder system including a coloring pigment, a body pigment, a glittering pigment, a spherical powder, etc. is mold filled in a dish-shaped container made of a metal such as aluminum or the like or a plastic.
Further, solid powdery cosmetic compositions are frequently carried, while put in a hand bag or the like. If the molded product has poor impact resistance, the molded product may be cracked or broken when it is dropped on a floor or when it is carried, while put in the hand bag or the like. Therefore, the product must reach such a level as assuring the impact resistance under use condition in an ordinary life. In addition, since a surface of the molded product of the solid powdery cosmetic composition is rubbed off with a small tool such as sponge puff or brush, which is applied onto a skin, a rubbed state onto the small tool and usability such as a skin-applied feeling are important qualities for the product.
The usability of such a solid powdery cosmetic composition is not only influenced by kinds, particle diameters, particle shapes and chemical compositions of powders blended and an oily agent as a binder, but also the usability frequently depends upon a method of mold filling a preparation thereof. Particularly, in order to assure the impact resistance, it is important to appropriately select a combination of them.
In case of a cosmetic preparation containing a large amount of an elastic and good-touch spherical powder, a flaky powder and a glittering powder having a high aspect ratio, etc., the moldability and the impact resistance are deteriorated. So, the kinds of powders and the kind of the oily agent blended as well as the molding method have been examined.
As the method of mold filling the solid powdery cosmetic composition, a method in which a base material of the cosmetic composition composed mainly of the powders is filled in a dish-like vessel and the resultant is compression molded (so-called press molding method) is commonly used. However, in this press molding method, it may be that air remains inside the molded product depending upon the composition of the cosmetic base material, which causes problems of molding disorders such as reduction in the impact resistance, peeling or cutting. In order to avoid such problems, a wet type molding method is often used (Patent documents 1 and 2). Further, a method in which the impact resistance is enhanced by surface-treating the powder has been examined (Patent documents 3 and 4).